Rotary well bore cleaner



July 19, 1960 a. T. ALEXANDER, JR., ETA!- 2,945,540

ROTARY WELL BORE CLEANER Filed April 7, 1958 2 Sheets-Sheet 1 ,4 TTOR/VEK July 19, 1960 G. T. ALEXANDER, JR., ETAL 2,945,540

ROTARY WELL BORE CLEANER Filed April 7, 1958 2 Sheets-Sheet 2 ATTOR/KQKINVENTORS United States Patent ROTARY WELL BORE CLEANER Granison T.Alexander, Jr., and Leroy Q. Gresham, Houma, La., assignors, by mesneassignments, to Gem Oil Tool Company, Inc., Houma, .La., a corporationof Louisiana Filed Apr. 1, 1953, Ser. No. 726,930 12 Claims. or.166-173) This invention relates to the cementing of a casing in a wellbore, and'more particularly to the surface conditioning of a bore wallport-ion by cleaning or removing the crust or cake of drilling muddeposited during the well drilling operation and preparing the wallsurface for a surface penetrating and tight bond of cement introduced tofill and close off the annular space surrounding a pipe casing at thecleaned surface.

Wall cleaning operations as commonly performed have been byreciprocating the casing up and down in the well bore to scratch throughthe mud encrusted surface by a large number of outwardly projectedscratcher tipped fingers carried by a collar clamped around the casingat a given portion in its length as predetermined by the region to becemented. Reciprocable scratcher assemblies when properly constructed to'do a reliable job are costly and necessitate the employment of numerousscratcher points to provide acircularly continuous working areathroughout the circumference of the casing.

.It is an object of the present invention .to provide a more effectivewall cleaner having only a few simple and inexpensive components topartake of easing rotation whereby to have a circular path of travel forworking the bore wall circumference.

A further object of the invention is to provide a rotary cleaner to be:fitted on the casing exterior with a cake scraping and cutting armpivotally mounted on a vertical axis and for oscillation from aninitially inwardly disposed inactive position out of contact with thebore wall to a radially outwardly projected bore wall engaged workingposition and which outward'swinging action is effected by a cutterpositioning control arm angularly related to the cutter for co-operativebearing engagement with the bore wall in initially maintaining thecutter arm retracted during descending longitudinal casing travel andthen compelling outward projection of the rockable cutter to wellsurface scraping contact after the casing has been fully lowered and isrotated to carry with it the pivot connection of the cutter.

Additional objects will become apparent during the course of thefollowing specification .having reference to the accompanying drawingwherein Fig. l is aside elevation with parts in section .of a segment ofthe improved cleaner assembly mounted on a casing prior to insertionwithin a well hole; two adjoining cutter spring wires being shown swungoutwardly from the casing and for convenience of disclosure beingillustrated by solid lines in an initial unstressed :semielliptical formfor comparison to broken line indications of other shapes assumed underworking stress variously applied .in sequence; the dotted line showingof the lowermost spring indicating a radially expanded bowing incompensation for a forced crowding together-of opposite end portions ofthe spring wire and the dotted line positionof-the upper springindicating a radial deflection of the bow and an accompanyingaxialelongation as will occur under well hole working conditions whenthe cutter is rotated in dragging engagemom with the bore wall; Fig. 2.is a fragmentary front 'ice elevation of a casing mounted cutterlocating strap as viewed in the direction of the arrows 2-2 in Fig. lbut with the semielli-ptical cutter straps swung back against themounting strap in preparation for descent into' the well hole andgenerally in the relationship of the parts as seen in Figs. 4 and 5 Fig.3 is a transverse section of the mounting strap for the device as online 3-3 of Fig. 1; Figs. 4 and 5 are transverse sections on lines44;and 55 respectively of Fig. 2 and show the cutter arm fully retractedas would be the case during longitudinal travel of the casing in a wellbore and prior to casing rotation; and Figs. 6 and 7 are transversesections similar to Fig. -4 but illustrating the rocking action of thecutter bar, Fig. 6 showing the position of the cutter bar immediatelyupon start of casing rotation and Fig. 7 showing the cutter bar in thefully outwardly projected cutting relation in which the cutter drags onand abrasively scrapes over the exposed face of the bore wall throughoutcontinued casing rotation.

In the drawings the hole or well bore through the earth formation 1 isshown as being lined by a thickness of mud cake 2 at the end of thedrilling operation and it is this cake which must be removed at one ormore vertical depths where a cementing operation is to be made forfilling the annular space which occurs between the bore wall and thewall 3 of the sectional casing inserted for lining the bore in the usualmanner. The .casing is first suspended in the well bore by the drillingderrick and is lowered in increments as casing sections are added andafter the installation of the casing has been completed the rigmechanism is employed to impart continuous rotation to the casing foreffecting the cleaning operation with the cutter of this invention. Forthe relation of parts as shown in the drawing, casing rotation can beconsidered as occurring in a clockwise direct tion, as indicated .by thearrows .in Figs. .6 and 7. To

maintain the wall 3 of the casing in substantiallyconcentric relationwith the well bore, the casing will have fitted to it one or moreconventional centralizers and such centralizers may be of the type whichhave :a number of radial spring arms fixed to the casing to project intoelastic bearing with the bore wall.

As shown in the drawings, the improved cake =cutter involves as a singleassembled unit a vertical pintle :p'in 4 hingedly connecting a mountingstrap 5 and one .01 more spring strips, each comprising a given lengthof steel wire of the type known in the trade as piano grade wire andpreformed to comprise an outwardly zbowed portion'or cutter loop 6throughout its major longitudinal extent'jand terminated at oppositeends in convolutions or portions 7 and 8 wrapped in coiled form toprovide pivot mounting eyes embraced on the pintle -pin4. When so hingedon the mounting strap 5, the flexible cutter loop 6 is free to swing orrock about the pivot :pin '4 toward and away from the face of themounting strap and is illustrated in Figs. 1, 6 and 7. in positionsprojected outwardly and in Figs. 2, 4 and -5 in positions seatedbackwardly against the strap 5. In the :initial preformed shape thespring wire loop follows a substantially semielliptical form in themanner shown .in full lines in -Fig. 1, which is the shape of the wirebow prior to being placed under stress. In this initial .bow shape, thecenter portion of the longitudinal extent .of the bow is spaced from itspivot axis a distance greater than the.

include short arm portions for producing a more shallow bow or U-shape,as shown in the drawing.

Between the longitudinally spaced apart hinge eyes 7 and 8, theunstressed and outwardly bowed wire loop normally lies in a planesubstantially radially related to the hinge axis. The bottom terminal ofthe spring wire extends laterally outwardly for a short distance fromthe lowermost coil 7 and in given angular relation such'as an angle ofapproximately ninety degrees to the vertical plane of the how 6, toprovide a short length leg 9 arranged to have stop abutment (see brokenline position, Fig. 2) with the mounting strip at the outwardlyprojected limit of oscillation of the cutter arm or bow 6. Above theupper coiled eye 8, the wire is bent as at 10 in a vertical planeangular to the bow, into a laterally projected U-shape, which iscoplanar with the leg 9 and also is adapted for abutment (see the brokenline position in Fig. 2 and the full line position in Fig. 7) with aportion of the mounting strip 5 for outwardly limiting the oscillationrange of the bowed cutter arm 6. From the upper end of the U-shaped stop10, the wire is again coiled upon itself as a pivot pin attachment eye11 and beyond the coil 11 the wire projects as an integral tang or leverarm extension 12 and is inclined upwardly and outwardly from the pivotaxis to a terminal tip which is spaced from the pivot axis a radialdimension predetermined in relation to a given installation and in anyevent slightly in excess of the radial dimension between the casing 3and the interior surface of the bore whereby to contact the bore surfacein use and in the manner later referred to in connection with Figs. 4and 6. The upwardly and outwardly extending terminal tang or lever arm12 also is angularly related to the vertical plane of the bowed cuttingarm 6 and the divergence of these two lever arms 12 and 6 as illustratedis on the order of about ninety degrees. Such spaced relation can bevaried so long as an operative co-operation of the arms with the wellbore wall is maintained throughout installation of the casing and whichcontemplates that during casing descent in the well the cutter arm 6will be held at its retracted limit of oscillation and away from thebore wall by reason of the frictional drag engagement with the wall bythe position control arm 12, as is seen in Fig. 4, and that duringsubsequent casing rotation with the cutting arm 12 swung out into wipingrelation with the wall and at its outwardly projected limit ofoscillation, the control arm 12 will be out of action and clear of thewall, as seen in Fig. 7, but that during a short increment of initialcasing rotation and while the hinged wire is being rocked through anintermediate portion of its oscillation range both arms will bemomentarily in engagement with the wall to insure operative positioningof the cutter arm 6 before frictional contact of the control arm 12 isbroken.

The mounting strip 5, as best seen in Fig. 3, can be easily formed of anarrow sheet metal strap bent along a longitudinal line with theopposite sides diverging to hear at their ends on the outside surface ofthe casing wall 3 while the apex is away from the casing. Atlongitudinally spaced intervals, pairs of transverse slits are cutthrough the apex and for a short distance into each of the legs and thematerial between each pair of slits is pressed inwardly, as at 13, toprovide a keeper bearing wall for co-operation with the apex portion ofthe strip in receiving and locating the pintle pin 4. The pin ends maybe headed over, as shown in Fig. 1, for retention with the mountingstrip 5.

In fastening the mounting strip 5 to a well casing, the side edges ofthe angular legs may be spot welded at several points to the casing.Alternately, the strip may be clamped to the casing as by means of twoor more flexible wires or banding cables 14, each of a length to fitaround the casing and the mounting strip 5 and to be secured at oppositeends by suitable fastenings, such as 4 terminal mounting heads 15-15 fora threaded tensioning stud 16.

In the region where the lower spring wire coil 7 embraces the pintle pin4, the central area of the strip 5 has a coil passing cutout or window17 which in the axial direction of the pintle pin is of a length onlyslightly greater than the length of the coiled eye 7. By opposite coilend abutment with the window top and bottom edges the coil is axiallylocated within the narrow confines of the window 17. The upper pivoteye, comprising the coils 8 and 11, similarly extends through an openingor window 18 which is of relatively great axial extent to permit the eyeto slide on the pin and accommodate axial elongation and shortening ofthe bowed arm 6 in compensation for its radial expansion andcontraction. Thus in Fig. 1 illustrating the parts prior to placement ofthe assembly within a well hole but with the cutter arms rocked towardbut not necessarily at the outermost limit established by the abutmentstops 9 and 10, the upper hinged eye of each bowed strip is illustratedin full lines as approximately centered Within the window space 18 andthe bowed portion 6 is shown by solid lines in an unstressed andpreformed normal loop shape and in which it projects from the hinge pina distance greater than annulus space in which the loop is to bereceived between the walls of the bore and easing. It will be apparent,therefore, that after the casing has been lowered into a well and thebow is brought in working contact with a wall surface being cleaned, itwill tend to conform to the wall and contract radially and may flattenout in the fashion indicated by broken lines in the upper portion ofFig. 1, in which case the upper pivot eye will have shifted upwardlywith the tang or control arm 12 in the dotted line position shown. Onthe other hand, relative downward pressure on the tang 12 will contractthe length of the loop whereby, as shown by the broken lines in thelower half of Fig. l, the upper spring eye will have moved downwardly inthe window 18 and the bowed portion 6 will have increased its radialprojection, as indicated by the broken lines. This illustration in Fig.1 comparatively demonstrates the result of downward pressure on the tang12 prior to entry of the casing in the hole and with the bowed portion 6in an outwardly rocked position. However, when the bow portion is rockedback away from the bore wall and is within the bore, as shown in Fig. 4,its longitudinal shortening will increase its curve projection in thesame manner. .Such bow increase will occur in advance of outwardswinging of the bow, as will later be referred to, and is for thepurpose of insuring bore wall contact by the bow upon its eventual swingout and prior to completion of the concurrent swing back of the controlarm 12, as explained in connection with the Fig. 6 illustration.

When the axial length of the bore surface to be cleaned in preparationfor cementing is greater than a single bowed strip can effectively work,it will be desirable to hinge on a common pintle pin a verticalsuccession of identical bowed wires and arrange them so that adjoiningends of succeeding wires overlap one another, as illustrated in Fig. 1.By way of illustration, an axial length of about five feet to be cleanedcan be effectively worked with a succession of five bowed strips, eachhaving the overlapping relation indicated in Fig. 1 for motiontransmitting contact with an adjoining strip, so that the succeedingstrips tend in a measure to co-operate with one another in unisonaloscillation between inactive and active positions.

In the use of the wall cleaner constructed as heretofore described, thecasing section with a single one of the units mounted thereon isintroduced into the well hole with the bowed cutter arm as in Fig. 4swung inwardly about its pivot pin 4 to extend forward therefrom in thedirection of eventual casing rotation. Accordingly the upwardly andoutwardly extending control arm 12 will project radially outwardly'andbe under elastic bending stress, inasmuch as its length is selected thatwith the arm free of bending strain, its terminal tip is farther fromthe pivot pin than the width of the annulus space, and the free end ofthe radially disposed spring arm 12 will ride on and be in .longitudinalslide bearing relation with the inner surface of the well'bore, or,.more particularly, with the inner surface of the mud cake liner. Duringthe lowering in operation with the casing maintained nonrotatable, theterminal tip of the control arm 12 will drag downwardly on the bore wallwith a one-way slipping clutch type of action. The elastic bearing andthe terminal tip will be offset toward the cutter arm 6 from thevertical plane containing the axis of the hinge pin 4. By reasonthereof, the control arm 12 will be held under elastic stress to resistoscillation and retain the bowed cutter arm 6 in stop abutment with themounting strap 5.

After descent of the casing has ended and placed thecutter at a desiredcleaning depth, the rig suspension mechanism will be operated to retractor raise the casing a short distance. Because of the upward and outwardextent of the control arm 12, its tip will have a braking action withand tend to dig into the wall and resist upward movement of the slidablehinge :eye afforded by the coils 8 and 11 at the upper end of the bowedportion. There will result a length shortening and radial expansion ofthe bowed portion 6 in readiness for being rocked toward contact withthe wall to be cleaned. Through the usual rotary machine, the raisedwell casing 3 can now be turned clockwise, whereupon the pivot pin 4will be carried forward in the direction of .rotation and away from thewall braked tip of the control arm 12 so as to oscillate or rock thepreviously expanded bow 6 outwardly toward the wall. Fig. 6 shows byfull lines the start and by broken lines an intermediate part of therange of swing with the bow coming into wall contact just before controlarm release. As this initial increment of rotation proceeds, theoscillation of the wire assembly about its axis in spaced parallelismwith the axis of rotation will bring the control arm 12 into trailingrelation with the circularly traveling pivot pin 4 and establishment of"bore wall contact by the how 6 swings the control arm inwardly towardthe casing. That is, in .advance of inaction of the control arm 12, theangularly spaced and radially expanded 'bowed portion 6 will have swungout and into contact with the wall (see Fig. 6) and once that contact isestablished, the bowed portion will hug the wall surface as the hingepin 4 advances. During such advance, the how will be squeezed betweenits hinge and the bore wall and placed under radial stress. Its curvedecreases to a flattened shape in elastic conformity with the wallsurface and its length elongates as permitted by wire yieldability andensuing complete disengagement of the wall clutching tip with back swingof the control arm 12. During continued rotation, the swing of thecutting how will be stopped by the limit stops 9 and in bearing with themounting strip 5 and the expansible spring wire bow 6 will trail thepivot pin 4 and continuously exert outward force on the mud film cakefor thinning it down by both cutting into and abrading its surface.

Casing rotation may be continued for as long as an hour or more,depending on the thickness and hardness of the mud cake to be scrapedoff, and after the cleaning operation has been satisfactorily completed,to expose the face of the formation, a cement slurry is introducedthrough the casing for controlled flow into the annular spacesurrounding the casing in the usual way and casing and cutter rotationis continued, whereby the parts of the cutting unit move through andkeep the cement slurry stirred for working out air pockets and fortroweling the wet cement into the surface of the formation as an aid toa firm cement bond. After the cement flow has completely shut downfurtherrotation disturbance is discontinued to enable the cement to setup.

Various modifications of the structure may be made without departingfrom the invention as set out in the attached claims.

What is claimed is:

1. "In a well bore cleaner assembly to be mounted on and rotated by acasing, a pintle pin mounting member, a series of scraper loops, meanspivotally, joining the loops at their opposite ends on said mountingmember for swinging travel from a retracted position to an outwardlyprojected position and each loop arranged in vertically spacedsuccession with a portion of each loop vertically overlapping a portion.of the next adjoining loop, said loops each having an upwardly and.outwardly projected extension angularly related to the loop and intrailing relation thereto with respect to the direction of easingrotation, each extension being arranged to project outwardly for borewall contact to maintain the loops retracted during casing descent andto respond to casing rotation by swinging backwardly and thereby causingthe loops to swing outwardly for rotational drag engagement with thebore wall.

2. In a cleaner as in claim 1 wherein the means pivotally joining theloops to the mounting member includes axially slidably fitted parts andenables relative movement .of the loop ends toward and from one anotherto accommodate change in loop length with loop expansion and contractionand wherein the loops are spring strips for elastic conformation to thebore wall surface.

3. In combination with a well casing to be cemented in a well bore, ofan outwardly bowed spring strip having its opposite ends verticallyspaced apart, .means pivotally mounting .on .said ends on the casing forswing travel of the bowed spring strip from a retracted positionadjacent the casing to an outwardly projected working position and acontrol arm carried by the strip and provided with a terminal tipportion angularly spaced from said bowed strip, said tip portion beingcngageable with the bore wall for holding the bowed strip in itsretracted position during lowering of the casing in the bore and forcompelling backward swing of the control arm :upon casing rotation tothereby swing the bowed ship outwardly into drag cleaning engagementwith the bore wall as casing rotation continues.

4. In combination, a well casing to be lowered and then rotated in awell bore, a vertical succession of spring loops, means pivotallymounting the same at vertically spaced apart points on the casing withend portions .of adjoining loops overlapping one another, the pivotalmounting of said loops accommodating their movement .from a retractedposition adjacent the casing and forward of their pivotal mountings inrelation to casing rotation and .to an outwardly projected bore wallengageable position and a control arm carried by each loop and projectedupwardly and outwardly in angular trailing relation with the loopwithrespect to the direction of casing rotation, said armbeing of a lengthto be engageable with the bore wall for holding the loop .in retractedpositionduring lowering of the casing and for compelling said loop toswing outwardly into wall engagement upon casing rotation.

5. A cement conditioning wall cleaner to be rotated with a well casingand thereby. dragged on the surface of a well bore wall, comprising alength of spring steel wire bowed throughout its major extent, coiledwire portions at opposite ends of the wire bow constituting pivotmounting eyes, pintle pin means to be carried by the casing andprojecting through the coiled portions on a substantially vertical axisand locating the wire bow for swinging movement between a retractedposition forward of said pintle pin means in relation to the directionof easing rotation and a bore wall engageable and outwardly projectedposition, a short wire extension projecting laterally from each coiledportion in a common vertical plane angularly spaced from the verticalplane of the wire bow and constituting abutment stops at said outwardlyprojected position of the wire bow, a wire continuation projectingbeyond one of said abutment stops and extending outwardly from thepintle pin means for a distance greater than the radial width of thecasing annulus space and terminating in a bore wall engageable portionin spaced relation with the wire bow in the direction of the arcuateswing path of said bow.

6. The cleaner of claim 5 wherein one of the pivot mounting eyes isaxially slidable relative to the pintle pin received thereby andaccommodates relative axial movement of said end coils upon elongationof the wire bow in compensation for a flattening thereof to bore wallconformation in the outwardly projected position of the wire bow.

7. A well bore cleaner of the character described, mounting means forattachment to a casing, a bore wall engageable scraper, a pivotalconnection joining said scraper with the mounting means on a pivot axisto extend in the longitudinal direction of the casing and accommodatethe swinging of the scraper between positions inwardly retracted towardand outwardly projected from said mounting means and a position controlarm fixedly joined to the pivoted scraper and provided with a bore wallengageable portion angularly outwardly extending from the scraper andswingable therewith to an outwardly projected position coincident withscraper retraction and to an angularly retracted position coincidentwith scraper projection. I

8. A well bore wall scraper assembly to be mounted on a casing and topartake of longitudinal and rotary travel with the casing duringinstallation thereof in a well bore, said assembly including a mountingmember for attachment to a casing, pivot pin connection means carried bysaid member on a pivot axis to extend longitudinally of the casing, arockable spring strip having a pivot portion fulcrumed bysaid pivot pinconnection means and a pair of divergently related arms joined to andprojected outwardly from said pivot portion, one of I said armsincluding a bore wall scraper portion extending in the longitudinaldirection of and laterally spaced from said pivot axis and beingrockable about said axis between angularly spaced positions, oneof'which is an active scraping position for co-operation of the scraperportion with the bore wall during use and the other of which is anonactive position in advance of said pivot axis with respect to thetravel direction in which the casing is to be rotated and the other ofsaid arms including a bore wall engageable portion rockable with saidscraper portion and between angularly spaced positions which, withrespect to casing rotary travel, are respectively slightly in advance ofand in trailing relation to said pivot axis.

9. A well bore wall scraper assembly to be mounted on a casing forsequential longitudinal and rotary movement with the casing, saidassembly including a mounting member to be fastened to a casing, alongitudinally extending scraper having a bore wall engageable positionoutwardly spaced from said mounting member, means pivotally connectingsaid scraper with the mounting member on a longitudinal axis forswinging movement between said wall engageable position and adisengageable position and means fixed to said scraper for swingingmovement therewith and terminated in a wall engageable tip portionangularly spaced about said axis from the scraper a distance tobepositioned for wall co-operative engagement outwardly from saidmounting member when the scraper is in its disengaged position and toswing back from its position of wall co-operative engagement and therebycompel scraper movement to wall engageable position upon forward rotarymovement of said mounting member.

10. In combination, a well casing having longitudinal and rotary travelwithin a well bore and a rotary well bore wall scraper comprising amounting member attached exteriorly of the casing, a longitudinallyextending bore wall scraper, means pivotally joining said scraper t0 themounting member on a longitudinal axis for swing ing travel of thescraper toward and outwardly from the casing and interengageable seatsurfaces carried by the scraper and by said mounting member andengageable to limit swinging travel of the scraper away from an inwardposition adjacent the casing and forward of said pivot axis in therotational travel of the casing and to a bore wall scraping position inwhich the scraper projects radially outwardly from the casing.

11. In combination, a casing having longitudinal and rotary movement ina well bore and a bore wall cleaner comprising an expansible bowed striphaving its opposite ends vertically spaced apart, means pivotallyconnecting said opposite ends to the casing on a vertical axis andaccommodating swinging of the strip between relative positions disposedinwardly toward and outwardly from the casing, said means being closelyfitted to and restricting axial movement of one of said ends andengaging the other end with axial clearance to permit axial move mentthereof in compensation for increased expansion of the bowed strip and acontrol arm fixed to and projected outwardly and upwardly from theaxially movable end and terminated in angularly spaced relation to thestrip, said control arm being of a length for well bore contact when thestrip is inwardly disposed to thereby resist outward swinging of thestrip during downward casing travel in the well bore and resist upwardmovement of the axially movable end with upward casing travel to therebyforcibly expand the strip and additionally causing outward swinging ofthe expanded strip when said axis is carried forward with casingrotation.

12. The combination as in claim 3 wherein said bowed strip is expansibleupon relative movement of its opposite ends one toward the other inresponse to upward casing travel when said terminal tip is in bore wallengaging relation and the pivotal mounting means co-operates with theends to accommodate such movement.

References Cited in the file of this patent UNITED STATES PATENTS

